Low-Dose Aspirin Found to Prevent Precancerous Condition

A daily dose of baby aspirin has been proven effective as a modest chemoprevention agent against the recurrence of colorectal adenomas, a precursor to colorectal cancer, according to a study published by the Norris Cotton Cancer Center at Dartmouth-Hitchcock Medical Center and Dartmouth Medical Center in the March 6 issue of The New England Journal of Medicine.

The Aspirin/Folate Polyp Prevention Study was conducted by a consortium of academic institutions across North America known as the Polyp Prevention Study Group. The randomized, double-blind study enrolled more than 1,000 participants, all of whom were previously diagnosed with colorectal adenomas. Robert S. Bresalier, M.D., now professor and chairman of M. D. Anderson's Department of Gastrointestinal Medicine and Nutrition, was thestudy's principal investigator at Henry Ford Health Sciences Center during his tenure there. Bresalier arrived at M. D. Anderson in July 2002.

"From descriptive epidemiologic studies, it appeared that aspirin would be an effective chemopreventive agent for colorectal neoplasia," Bresalier says. "This is really the first prospective, randomized trial and the strongest indication to date demonstrating aspirin's significant effect on recurrence of adenomas, which are precursors to colorectal cancer."

From 1994 to 1998, eligible participants underwent a baseline colonoscopy and were tested to determine their tolerance of aspirin. Participants then were randomized to take either 81 mg (equivalent to dosage of a baby aspirin), 325 mg of the drug, or a placebo daily. A follow-up colonoscopy was conducted approximately three years after enrollment.

According to study results, there was approximately a 19 percent reduction in recurrence of adenomas in the group taking the low-dose aspirin, compared to those taking a sugar pill (placebo), and a 4 percent reduction for those taking the higher dose. Even more significant, Bresalier says, was that the relative risk of advanced adenomas, lesions more likely to be precursors to cancer, was reduced by 41 percent in those taking low-dose aspirin.

Still, even at low doses, aspirin does have side effects, including the rare incidence of stroke. Bresalier cautions about a blanket recommendation for healthy individuals to take the drug.

Investigation into folate as a chemopreventive agent for the same precancerous condition is still ongoing.